An undergraduate tutorial on wallpaper groups, with illustrations of the 17 wallpapers groups and a wallpaper gallery. Technically, the derivation of all discontinuous groups of rotation and translation in the plane. Contents include: Some Theorems on Rotation and Translation; The Discontinuous Groups of Rotation and Translation in the Plane; Derivation and Classification of Groups; Appendix: The 17 Wallpaper Groups (with a Wallpaper gallery); and References and Related Web Sites. Hosted by the Math Forum.